FIELD OF THE INVENTION
Present disclosure relates to a fuse failure indicator unit for automotive applications. More specifically, the present disclosure relates to a fuse failure indicator unit for two-wheeler, three-wheeler and four-wheeler that indicates failure of a fuse to an end-user such as the driver or a servicing technician.
BACKGROUND OF THE INVENTION
In the field of automation, individual circuit components are typically protected from short-circuiting and excessive currents by a fuse or a circuit breaker interposed between the component and a power supply. In other words, the electric circuits have fuses to protect vehicle subsystems and other electrical loads such as radiator fans, solenoids, electric motors, electronic control units (ECUs) etc. Large numbers of such protection fuses may be found within any given system, depending upon the number of electric circuits contained therein.
This has given rise to the need for fuse and circuit breaker status indicators which allow for the easy and rapid location of a tripped, failed or "blown" electric load or vehicle subsystem. Specially, for some critical loads such as radiator fan control, protective relays etc., it is even more important to monitor for failure of said fuses protecting said critical loads. The reason being, in event of failure of the fuses protecting said critical loads do not cause immediate vehicle malfunction and hence may not be noticed by the driver. However, eventual non-operation of these critical loads due to fuse failure can lead to catastrophic consequences especially when these devices need to operate to avert an emergency situation. For example, in case of a radiator fan control, if the fuse protecting the fan control fails and the radiator is heated, it may not affect the vehicle immediately. But, after some time, it affects the vehicle such as making the vehicle stop in midway.
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In another situation, a driver/servicing technician needs to quickly diagnose the fuse failure using a simple instrument. This is relevant especially when the vehicle breaks down in a remote place and expert servicing manpower/tools like multi-meter are not available. However, in the existing technology, if the fuse blows, it requires extensive time of skilled technicians to locate the failed fuse and replace it.
There exist some solutions in the form of simple fuse-failure indicator. However, the existing solutions face many problems. For example, in case of in-vehicle use, the existing indicator units are not equipped with in-built transient protection, compromising their own reliability. In case of a stand-alone fuse failure indicator as a servicing tool, available solutions are not integrated with fuse removal tools such as a fuse puller. Also, the existing fuse failure indicator may not work in at the higher battery voltage for example 32V, since at this voltage range, the fuse failure indicator blows up. Further, it is important that such fuse and/or circuit breaker status indicators must remain electrically isolated from the circuits being protected to ensure they do not affect the performance of the protected circuits. In addition, the indicators must not significantly compromise the isolation between the protected circuitry and the power source after a fuse has blown or a circuit breaker tripped.
Hence, there is a need to provide a fuse failure indicator unit which immediately informs the driver of the vehicle about the fuse failure and also which comes with in-built transient protection.
OBJECT OF THE INVENTION
An object of the present disclosure is to provide an in-vehicle fuse failure indication unit with in-built transient protection.
Another object of the present disclosure is to provide a method for indicating failure of a fuse.
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SUMMARY OF THE INVENTION
In an aspect, the present disclosure relates to a fuse failure indicator unit comprising an illumination source and a constant current circuit operatively connected to a fuse and the illumination source. The constant current circuit further comprises a sensing element and a constant current source, wherein, the constant current circuit is configured to illuminate the illumination source, when the fuse fails to operate.
In another aspect of the present disclosure the sensing element comprises a sensing transistor (Q1) connected to a resistor (R1) and a resistor (R3).
In yet another aspect of the present disclosure, the constant current source comprises a control transistor (Q2) connected to a power source, the resistor (R1) and the resistor (R3).
In still another aspect of the present disclosure the voltage across resistor (R3) increases when the fuse fails to operate due to at least one of over-current or other malfunction, causing the sensing transistor (Q1) to enter in conducting mode.
In yet another aspect of the present disclosure the sensing transistor (Q1) draws the current away from the control transistor (Q2), causing the control transistor (Q2) to provide constant current.
In still another aspect of the present disclosure, the constant current source is configured to provide constant current to the illumination source to indicate the failure of the fuse.
In yet another aspect of the present disclosure the constant current circuit provides transient protection.
In still another aspect, the present disclosure relates to a method for indicating failure of a fuse. Said method comprising sensing the failure of the fuse, activating
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the constant current circuit to provide constant current to an illumination source and illuminating the illumination source to indicate the failure of the fuse.
Those skilled in the art will appreciate that the conception upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of the invention. It is important therefore that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of the invention.
The following paragraphs are provided in order to describe the best mode of working the invention and nothing in this section should be taken as a limitation of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects and advantages of the present disclosure will be readily understood from the following detailed description with reference to the accompanying drawings, where like reference numerals refer to identical or similar or functionally similar elements. The figures together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the aspects/embodiments and explain various principles and advantages, in accordance with the present disclosure wherein:
Figure 1 depicts the basic block-level system schematic of the fuse failure indicator unit connected across a fuse according to an embodiment of the present disclosure.
Figure 2 depicts a component level circuit schematic implementation of the fuse failure indicator unit shown in fig.1 according to an embodiment of the present disclosure.
Figure 3 depicts a flow chart illustrating method steps for indicating the failure of the fuse.
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DESCRIPTION OF THE PRESENT DISCLOSURE
Referring now to the drawings, there is shown an illustrative embodiment of the fuse failure indicator unit according to the present disclosure. It should be understood that the disclosure is susceptible to various modifications and alternative forms; specific embodiments thereof have been shown by way of example in the drawings and will be described in detail below.
Before describing in detail embodiments, it may be observed that the novelty and inventive step that are in accordance with the present disclosure resides in the circuit assembly of the fuse-failure indicator unit for vehicles such as two-wheelers, three wheelers and four wheelers. It is to be noted that a person skilled in the art can be motivated from the present disclosure and modify the various constructions of assembly, which may vary from vehicle to vehicle. However, such modification should be construed within the spirit and scope of the invention. Accordingly, the drawings show only those specific details that are pertinent for understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device that comprises a list of components does not comprise only those components but may comprise other components not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
Figure 1 depicts the basicblock-level system (100) schematic of the fuse failure indicator unit connected across a fuse. The system (100) may comprise a fuse (101), a battery (103), a load (105) and fuse failure indicator unit (107). As shown in fig. 1, the fuse (101) is connected between the battery (103) and the load (105).
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In an examplary embodiment of the present disclosure, the indication unit (107) may have two terminals and is connected across the fuse (101). The indication unit (107) as shown in fig. 1, may comprise a constant current circuit (107a) and an illumination source (107b). In an embodiment, the illmination source (107b) may be a light emitting diode (LED). It should be noted that any electric component, which has the cabipility of illuminating upon receiving a current can be used as an illumination source. The constant current circuit (107a) of the indicator unit (107) further comprise a sensing element (107c) and a constant current source (107d). In an exemplery embodiment, any of said elements (107a, 107b, 107c, 107d) may also be placed outside the indication unit (107).
The constant current circuit (107a) of the indiactor unit (107) may provide constant current to the illumination source (107b) to indicate the failure of the fuse (101). In an embodiment, the sensing element (107c) of the constant current circuit (107a) is configured to sense the voltage across the terminals of the unit (107) for detecting the failure of the fuse (101). When the fuse (101) is operative, the voltage across the sensing element (107c) is zero and the indicator unit (107) is bypassed and hence the illumination source (107b) does not illuminate.
However, when a fuse (101) fails to operate due to at least one of over-current, or other malfunction, the sensing element (107c) senses high voltage across the unit (107) and powers the constant current source (107d) circuit to operate in constant current mode. The constant current then flows through the illumination source (107d) lighting the same, thereby notifying the end-user regarding the fuse failure. The working of the unit (107) is explained in detail with reference to fig. 2.
In an embodiment, the constant current circuit (107a) may comprise of componets rated to withstand voltages higher than the transient pulses occuring in an automotive vehicle environment as per ISO 7637 part 2. The constant current circuit (107a) may ensure that the current level through the illumination source (107b) is limited to a constant value over the battery voltage 8 volts. Also, it may limit the illumination source (107b) current to safe value (below rated illumination
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source current) upto transient voltages of the order of 200 volts. This allows for the selection of a low power compact illumination source which glows with equal brightness through the 8 to 32 voltage range and yet is protected from transients. This feature may obviate the use of a shunt transient protection units normally employed for automotive purposes which apart from making the solution expensive would have added a third terminal to the unit making it cumbersome from integration point of view. Hence, the disclosed fuse failure indicator unit (107) may provide protection against transient voltage. Also, it can opeeate smoothly through 8-32 voltage range.
Fig. 2 depicts the component level circuit diagram of the system (100) of fig. 1. A sensing transistor (Q1), a control transitor (Q2) and resistors R1, R3 may form a low cost two terminal constant current cicrcuit (107a) of fig. 1. As shown in fig. 2, the unit (107) is connecetd across the fuse (101).
In an embodiment, the sensing element (107c) of the constant current circuit (107a) may comprise of a sensing transistor (Q1) and the constant current source (107d) of the constant current circuit (107a) may comprise a control transitor (Q2). The illumination source (107b) may comprise a diode D2. As shown in fig. 2, the sensing transistor (Q1) is connected to the resistors R1, R3. The control transistor (Q2) is connected to a power source (103) and the resistors R1, R3. The output of the constant current circuit (107a) is connected to the diode D2.
When the fuse fails to operate, the voltage across R3 may increase, which causes the base-emmitter volatge across the sensing transistor Q1 to increase. When the battery voltage further increase, the voltage across R3 may not increase beyond 700 mV but the sensing transistor Q1 may start conducting, which may drive away the current from the base of the control trasistor Q2. In response, the control tarnsistor Q2 provides constant current to the illumination source (107b) causing the illumination source (107b) to illuminate indicating the failure of the fuse (101). In this way, the control transistor Q2 may act as constant current source. Thus, the discosed unit (107) may limit the circuit current value to 700mv/R3 mA
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through closed loop control action supported by both transistors and resistors. Therefore, the illumination source (107b) may not blow up even due to transient voltage.
In an embodiment, the transistors Q1 and Q2 are adequately rated to withstand voltages of around 200 Volts. Diode D1 may provide reverse polarity protection while resitor R1 may limit the voltage appearing across current source, thus minimizing transitor wattage requirements. Thus, the present disclosure provides a fuse failure indicator unit with an in-built transient protection and may function in the range of 8-32 battery voltage. It is to be noted that a person skilled in the art may use any other suitable componet other than the disclosed components to achieve the desired objective.
Further, the disclosed unit (107) may be incoporated into a fuse removal kit which allows a technician to remove a blown fuse easily as the blown fuse can be located by using the same kit. In this embodiment, the fuse faliure indiactor unit may work in the same manner as explained above. For example, when the kit is connected across a fuse, if the fuse is blown up, the illumination source glows. Otherwise the illumination source does not glow. In this way, the technician may remove the blown up fuse after the illumination source glows. In this way, the technician does not need to use two different kits to check and remove the blown up fuse, thus saving time and efforts.
Fig. 3 discloses a method for indicating failure of a fuse. As shown in fig. 3, at step 301, the unit (107) senses failure of the fuse (101). At step 303, the constant current circuit (107a) is activated to provide constant current to an illumination source (107b). At step 305, the illumination source (107b) is illuminated to indicate the failure of the fuse (101).
The scope of the present disclosure is not limited to the explained embodiments only. A person skilled in the art can easily extend the scope and use of the invention to any other suitable field. The present disclosure is described with
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reference to the figures and specific embodiments; this description is not meant to be construed in a limiting sense. Various alternate embodiments of the invention will become apparent to persons skilled in the art upon reference to the description of the disclosure. It is therefore contemplated that such alternative embodiments form part of the present disclosure.

We Claim:
1. A fuse failure indicator unit, comprising:
an illumination source; and
a constant current circuit operatively connected to a fuse and the
illumination source, the constant current circuit comprises:
a sensing element; and
a constant current source, wherein, the constant current circuit is configured to illuminate the illumination source, when the fuse fails to operate.
2. The unit as claimed in claim 1, wherein the sensing element comprises:
a sensing transistor (Q1) connected to a resistor (R1) and a resistor (R3).
3. The unit as claimed in claim 1, wherein the constant current source
comprises:
a control transistor (Q2) connected to a power source, the resistor (R1) and the resistor (R3).
4. The unit as claimed in claim 2, wherein the voltage across resistor (R3) increases when the fuse fails to operate due to at least one of over-current, or other malfunction, causing the sensing transistor (Q1) to enter in conducting mode.
5. The unit as claimed in claim 4, wherein the sensing transistor (Q1) draws the current away from the control transistor (Q2), causing the control transistor (Q2) to provide constant current.
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6. The unit as claimed in claim 5, wherein the constant current source is configured to provide constant current to the illumination source to indicate the failure of the fuse.
7. The unit of claim 1, wherein the constant current circuit provides transient protection.
8. A method for indicating failure of a fuse, the method comprising: sensing the failure of the fuse;
activating the constant current circuit to provide constant current to an
illumination source; and
illuminating the illumination source to indicate the failure of the fuse.